Sperm competition was investigated in Callosobruchus maculatus on Vigna unguiculata seeds in the laboratory at 30°C, 35% RH and LD 16:8. The sterile male and genetic marker techniques for estimation of sperm precedence were compared. The proportion of offspring fathered by the second male (P₂ values) obtained by the 2 methods were similar (0.82 and 0.85 for the sterile male and genetic marker methods, resp.). It is suggested that both methods are suitable for studying sperm precedence if the appropriate correction factors are applied. The importance of general fertilization ability, differential fertilizing capacity and differential zygote mortality were examined also.